(Phys.org) —Scientists have many tools for measuring the cosmic structures of the universe, which includes structures such as galaxies, galaxy clusters, and intergalactic gas. Cosmic structures can be observed ...

(Phys.org) —The faint background glow that exists throughout the Universe, called the Cosmic Microwave Background (CMB), is made of photons that have been scattering since the universe was just 400,000 ...

(Phys.org) —In Jonathan Swift's 1726 book "Travels into Several Remote Nations of the World. In Four Parts," the miniature Lilliputians experience the world very differently from the giant Brobdingnagians.

(Phys.org) —Scientists have a great deal of evidence to support the fact that the universe contains much more baryonic matter than baryonic anti-matter, a phenomenon known as baryon asymmetry. Baryons, ...

(Phys.org)—If you've read about how modern cosmology may imply that, in an infinite universe, the existence of planets and the life forms that live on them must be repeated an infinite number of times, ...

(PhysOrg.com) -- Inflation, the brief period that occurred less than a second after the Big Bang, is nearly as difficult to fathom as the Big Bang itself. Physicists calculate that inflation lasted for just ...

Despite earlier reports of a possible detection, a joint analysis of data from ESA's Planck satellite and the ground-based BICEP2 and Keck Array experiments has found no conclusive evidence of primordial ...

Researchers at the University of Southampton have proposed a new fundamental particle which could explain why no one has managed to detect 'Dark Matter', the elusive missing 85 per cent of the Universe's ...

A team of engineers and scientists has identified a source of electronic noise that could affect the functioning of instruments operating at very low temperatures, such as devices used in radio telescopes ...

An observatory run by the University of Utah found a "hotspot" beneath the Big Dipper emitting a disproportionate number of the highest-energy cosmic rays. The discovery moves physics another step toward ...

(Phys.org) —Physicists Joseph Silk of Institut d'Astrophysique de Paris and Jens Chluba of Johns Hopkins University have together published a Perspective piece in the journal Science, where they discus ...

The Baryon Oscillation Spectroscopic Survey (BOSS), the largest component of the third Sloan Digital Sky Survey (SDSS-III), pioneered the use of quasars to map density variations in intergalactic gas at high ...

Cosmic microwave background radiation

In cosmology, cosmic microwave background (CMB) radiation (also CMBR, CBR, MBR, and relic radiation) is a form of electromagnetic radiation filling the universe. With a traditional optical telescope, the space between stars and galaxies (the background) is pitch black. But with a radio telescope, there is a faint background glow, almost exactly the same in all directions, that is not associated with any star, galaxy, or other object. This glow is strongest in the microwave region of the radio spectrum, hence the name cosmic microwave background radiation. The CMB's discovery in 1964 by radio astronomers Arno Penzias and Robert Wilson was the culmination of work initiated in the 1940s, and earned them the 1978 Nobel Prize.

The CMBR is well explained by the Big Bang model – when the universe was young, before the formation of stars and planets, it was smaller, much hotter, and filled with a uniform glow from its white-hot fog of hydrogen plasma. According to the model, the radiation from the sky we measure today comes from a spherical surface called the surface of last scattering. As the universe expanded, both the plasma and the radiation filling it grew cooler. When the universe cooled enough, stable atoms could form. These atoms could no longer absorb the thermal radiation, and the universe became transparent instead of being an opaque fog. The photons that were around at that time have been propagating ever since, though growing fainter and less energetic, since the exact same photons fill a larger and larger universe. This is the source for the term relic radiation, another name for the CMBR.

Precise measurements of cosmic background radiation are critical to cosmology, since any proposed model of the universe must explain this radiation. The CMBR has a thermal black body spectrum at a temperature of 2.725 K, thus the spectrum peaks in the microwave range frequency of 160.2 GHz, corresponding to a 1.9 mm wavelength. The glow is almost but not quite uniform in all directions, and shows a very specific pattern equal to that expected if the inherent randomness of a red-hot gas is blown up to the size of the universe. In particular, the spatial power spectrum (how much difference is observed versus how far apart the regions are on the sky) contains small anisotropies, or irregularities, which vary with the size of the region examined. They have been measured in detail, and match what would be expected if small thermal fluctuations had expanded to the size of the observable space we can detect today. This is still a very active field of study, with scientists seeking both better data (for example, the Planck spacecraft ) and better interpretations of the initial conditions of expansion.

Although many different processes might produce the general form of a black body spectrum, no model other than the Big Bang has yet explained the fluctuations. As a result, most cosmologists consider the Big Bang model of the universe to be the best explanation for the CMBR.